Table 2.
Association of age at menarche with tumor-defined characteristics of breast cancer
| Age at menarche, years | |||||
| Tumor characteristic | ≤11 | > 11 and ≤13 | > 13 and ≤14 | > 14 | P valuea |
| Tumor size | |||||
| 1–10 mm | 47 (28) | 258 (26) | 183 (27) | 153 (29) | |
| 11–20 mm | 76 (46) | 414 (43) | 302 (44) | 250 (47) | |
| ≥21 mm | 43 (26) | 304 (31) | 199 (29) | 129 (24) | 0.188 |
| Grade | |||||
| Low | 12 (10) | 98 (15) | 66 (14) | 71 (20) | |
| Medium | 50 (44) | 270 (40) | 214 (46) | 136 (39) | |
| High | 52 (46) | 304 (45) | 188 (40) | 141 (40) | 0.037 |
| ER status | |||||
| Positive | 91 (73) | 145 (20) | 113 (23) | 302 (79) | |
| Negative | 34 (27) | 564 (80) | 381 (77) | 78 (21) | 0.309 |
| PR status | |||||
| Positive | 84 (69) | 224 (32) | 181 (37) | 252 (68) | |
| Negative | 38 (31) | 473 (68) | 305 (63) | 121 (32) | 0.250 |
| Lymph node involvement | |||||
| Absent | 104 (63) | 630 (66) | 456 (68) | 374 (72) | |
| Present | 60 (37) | 329 (34) | 217 (32) | 146 (28) | 0.052 |
| Histology | |||||
| Ductal | 124 (75) | 692 (71) | 503 (73) | 383 (72) | |
| Lobular | 24 (14) | 118 (12) | 78 (11) | 62 (12) | |
| All other | 18 (11) | 165 (17) | 108 (16) | 87 (16) | 0.509 |
aPearson chi-square tests of association between groups. ER, estrogen receptor; PR, progesterone receptor.